The present invention is directed to an adaptor with a suction surface for a suction pipette which adaptor will adapt the size of the suction surface to a size of an electronic component to be picked up by the suction pipette and deposited on an assembly surface. The suction pipette and adaptor are particularly useful in an employment in an SMD-automatic equipping machine for surface mounting of components on a printed circuit board.
In SMD-technology (surface mounted device), electrical components are picked up and transported by an automatic equipping machine, which utilizes a vacuum suction pipette. The components are then set down for assembly on a printed circuit board. For the equipping of large components, correspondingly large adaptors with correspondingly large retaining forces are required. Given an unmodified size of the suction pipette, a so-called assembly adaptor is employed therefor. These adaptors, which are generally automatically exchanged by the equipping head, adapt the suction pipette attached thereto to various body surfaces of the different electronic components. In the ideal case, it has been proven that the axis of the suction pipette should extend orthogonally to the surface of the pc board which is to be equipped. This surface is referred to as an assembly surface. Since the presently known and employed adaptors establish a rigid connection between the adaptor and the pipette, the plane of the suction surface is not variable in the handling of a larger electronic component and results in various problems.
If, in the case of an acceptance of an electronic component by a suction pipette with an attached adaptor, the end face of the adaptor, which forms the suction surface, is not adjusted to extend in a parallel direction relative to the surface of the components, errors in the pick up may occur. This is due to the fact that any angle between the suction surface and the surface component provides a gap through which air can be sucked so that the component is not sucked-up at all or, possibly, is attached to the adaptor in a crooked or misaligned fashion.
Once a suction pipette with an adaptor has picked up the component, the next important step is the adjustment of the plane of the connecting legs of the component relative to the surface of the pc board which is to be equipped. If the plane of the end of the legs and the plane of the surface to be equipped are not parallel, an uncontrolled movement may result when the component is set down, for example causing a distortion in the position of the component on the board due to slippage.
One possibility to determine the position of the component, which is held on the suction pipette, is to place the component between the pick-up step and the placing step on a measuring plane and to measure the difference between the plane of the ends of the legs and the measuring plane. The measuring plane, in this case, will extend parallel to the pc board's assembly surface so that the situation can be simulated when the assembly is done. If, however, the component is tilted relative to the measuring plane, a false measurement can result.